The proposed investigation will concern itself with the biochemical characterization of the isolated gap junction protein, and with electron microscope and x-ray diffraction studies of the junction structure. A pure preparation of hepatic gap junctions is available in reasonable quantity by adapting continuous flow and zonal centrifugation to already published isolation techniques. X-ray diffraction studies will include analysis of sharp, on-plane hexagonal reflections which extend to 25A resolution. Additional resolution plus intensity analysis of the maxima from both the hexagonal and profile diffraction patterns will shed light on the arrangement of protein and lipid in this differentiated membrane fragment.